Preheat oven to 375 degrees F.
In a large saute pan, melt butter. When it’s foaming, add shallots and cook until softened. Add mushrooms and thyme and cook until mushrooms are golden. Let cool slightly.
Whisk eggs and cream together and season with salt and pepper.
Sprinkle bottom of pie shell with asiago cheese. Add cooled mushrooms and pour cream and egg mixture over top. Bake for 25-30 minutes, or until firm in centre and golden brown.